1. Field of the Invention
The present invention relates to a mobile terminal, and more particularly, it relates to a mobile terminal comprising an antenna.
2. Description of the Background Art
A mobile terminal comprising an antenna is known in general, as disclosed in each of Japanese Patent Laying-Open Nos. 2007-166533, 2006-145314, 61-200702 (1986) and 3-280625 (1991), for example.
The aforementioned Japanese Patent Laying-Open No. 2007-166533 discloses a folding portable radio apparatus (mobile terminal) comprising a plate-like upper housing provided with a display portion, a plate-like lower housing provided with operating buttons and the like, an intermediate housing provided between the upper housing and the lower housing and a patch antenna for receiving a GPS (global positioning system) having a circularly polarized wave characteristic, provided in the intermediate housing. The upper housing is rotatable (turnable) in a horizontal plane with respect to the lower housing through the intermediate housing, so that the folding portable radio apparatus can be used by vertically and horizontally changing the display portion of the upper housing without changing the direction of the lower housing. The patch antenna provided on the intermediate housing is formed to have directivity in a zenith direction (GPS satellite side) when the lower housing is placed on the horizontal plane. Thus, in the folding portable radio apparatus described in the aforementioned Japanese Patent Laying-Open No. 2007-166533, the patch antenna is provided on the intermediate housing turnable in the horizontal plane with the upper housing, so that directivity can be directed in the zenith direction without changing the direction of the directivity due to rotation of the intermediate housing (patch antenna) also when the upper housing is rotated in a state where the lower housing is arranged on the horizontal plane and the display portion vertically and horizontally changes in the horizontal plane.
The aforementioned Japanese Patent Laying-Open No. 2006-145314 discloses a positioning device (mobile terminal) comprising upper and lower housings, a satellite radio receiving antenna of a linearly-polarized wave (horizontally-polarized wave) and a communication antenna of a linearly-polarized wave (vertically-polarized wave), wherein the plane of polarization of the satellite radio receiving antenna and the plane of polarization of the communication antenna (the vertically-polarized wave and the horizontally-polarized wave) are orthogonal to each other. This satellite radio receiving antenna has directivity extending in a vertical direction, and a radio wave from an extensional axial direction of the antenna orthogonal to the vertical direction is unlikely to be received. The planes of polarization of the satellite radio receiving antenna and the communication antenna are orthogonal to each other, and hence the satellite radio receiving antenna is inhibited from receiving the radio wave transmitted/received from the communication antenna.
The aforementioned Japanese Patent Laying-Open No. 61-200702 discloses an antenna switching portable radio (mobile terminal) comprising a housing, a first inverted F antenna and a second inverted F antenna provided on both side surfaces of the housing opposed to each other respectively, a detector detecting inclination of the housing, a high-frequency signal switch switching connection from one of the first and second inverted F antennas to the other of the first and second inverted F antennas and a receiver and a transmitter provided on a side surface (front surface) in a direction orthogonal to the side surfaces provided with the first and second inverted F antennas. The portable radio (housing) is largely inclined when calling in a state where a user puts his ear against the receiver and moves the transmitter to his mouth. Thus, this antenna switching portable radio is so formed that a detecting portion detects the inclination of the antenna switching portable radio, and the high-frequency signal switch transmits/receives a radio wave on the basis of output from the detecting portion by connection to the inverted F antenna located on an upper side (in the vertical direction) among the first and second inverted F antennas provided on the both side surfaces of the housing.
The aforementioned Japanese Patent Laying-Open No. 3-280625 discloses a portable wireless communication device (mobile terminal) comprising a housing, a plurality of antennas, a selection portion for performing antenna diversity communication selecting an antenna having good receiver sensitivity from the plurality of antennas and switching to the same and a receiving portion connected to the respective antennas. This portable wireless communication device is so formed that correlation between radiation characteristics of the plurality of antennas is reduced by connecting the plurality of antennas to a circuit substrate or ground pattern separately provided.
In the aforementioned folding portable radio apparatus described in Japanese Patent Laying-Open No. 2007-166533, however, the patch antenna provided on the intermediate housing is formed to have directivity in the zenith direction in the state where the lower housing is placed on the horizontal plane, while the user must operate while watching the display portion when using the display function (GPS function) of the positional information by the GPS. Thus, when the user grasps the lower housing and uses in a state of holding while inclining the display portion at an easily visible angle, the directivity of the patch antenna is directed not to the zenith direction (GPS satellite side) but to a direction of the user and hence the directivity of the patch antenna is disadvantageously directed in the zenith direction when the user grasps and uses the apparatus.
In the aforementioned positioning device described in Japanese Patent Laying-Open No. 2006-145314, the satellite radio receiving antenna has directivity extending in the vertical direction (direction of gravitational force), and the radio wave from the extensional axial direction of the antenna orthogonal to the direction of gravitational force is unlikely to be received, and hence when the housing is rotated and the direction of the device itself is horizontally inclined, the directivity of the satellite radio receiving antenna is horizontally inclined and a satellite radio wave enters from the extensional axial direction of the satellite radio receiving antenna, and the satellite radio wave is disadvantageously unlikely to be received. Thus, when the direction of the positioning device is changed to be used, the directivity of the satellite radio receiving antenna can not be disadvantageously directed in the zenith direction.
In the aforementioned antenna switching portable radio described in Japanese Patent Laying-Open No. 61-200702, the plurality of antennas, the detector of inclination and the high-frequency signal switch must be provided in order to suppress reduction of the receiver sensitivity due to change of an attitude of the device, and hence the number of components is disadvantageously increased.
In the aforementioned portable wireless communication device described in Japanese Patent Laying-Open No. 3-280625, the plurality of antennas, the circuit substrate or ground pattern connected to the plurality of antennas and separately provided and the dedicated selection portion must be provided in order to perform antenna diversity communication selecting the antenna having good receiver sensitivity from the plurality of antennas and switching to the same, and hence the number of components is disadvantageously increased.